The present invention relates to a method for the pulverization or granulation of nuts and seeds.
Nuts in general among fruits are formed by strong hardening of the epicarp while the pericarp as a result of the growth of the ovarian walls is relatively thin and the seminal nuclei, i.e. embryo and albumen, are used for food.
"Seeds" refer to such seeds of plants other than fruit for example seeds of vegetables, oils and fats, etc.
Nuts of various kinds all contain lipids in a high content of, usually, in the range from about 47 to about 77%. Seeds also contain high amount of lipids, usually in the range from about 30 to 55%. These nuts and seeds have a high calorific value of 500 kilocalorie (kcal)/100 grams or larger so that they belong to a class of important foods with a high nutritive value. The high content of lipids, on the other hand, is accompanied by disadvantage that the fats and oils contained therein are susceptible to oxidation when nuts or seeds are prolongedly kept in air to cause great decrease in the taste and flavor so that long-term storage of nuts and seeds is undesirable and should be avoided. When nuts and seeds absorb moisture, in addition not only is air oxidation of the oils and fats contained therein is accelerated but also the inherently pleasant touch to teeth thereof may be entirely lost so that it is essential that nuts and seeds are stored in a moistureproof container under a condition lean of air.
As is known as the uses of nuts and seeds, they are used as an accessory additive in cooking and confectionary preparation or eaten as such as a relish food in alcoholic drinking. At any rate, nuts and seeds are served as keeping the original form or in the form of relatively coarse grains although nuts and seeds may be processed into a pasty form such as peanut butter as a very specific limited case. Attempts of pulverization have been made of almond and several other specific nuts though without success for the practical use of the powder because of the poor storability of the powder due to the great hygroscopicity.
When pulverized or granulated porducts of nuts and seeds be available, the application fields of these nuts and seeds in food processing would be greatly expanded and a complete change would be caused in the aspect of utilization of nuts and seeds in food industry. Even by setting aside the conventional applications, such a pulverized or granulated product of nuts and seeds can be an extending additive in a variety of food bases such as semiprocessed and frozen food of minced meat, a frosting powder on certain dishes, a base material of snack food and noodles and the like as only a part of possible applications.
Despite the eager desire to pulverize or granulate nuts for the expansion of the application fields as is mentioned above, no successful method has yet been developed for obtaining a dry powder of nuts because a paste is always formed by the pulverization of nuts containing a large amount of lipids due to the exudation of the oily matter. Even when nuts are coarsely ground with an object to reduce exudation of the oily matter, air oxidation of the oily matter during storage is unavoidable to cause great decrease of the value as a commercial product. Further, several plant seeds are known as edible including, for example, pumpkin seeds, sunflower seeds, pine nuts and the like. Similar problems to those in nuts above described are involved also in these edible seeds so that the application fields thereof are equally limited.